**Abstract**

We examine two studies on the prevalence and comorbidity of anxiety and depressive disorders in Japanese patients in primary care settings. The PRIME-MD study (Primary Care Evaluation of Mental Disorders) in Japan was conducted in seven primary care sites. The sample group included 601 adult patients (249 males, 352 females, mean age = 58.9 years, SD = 16.5). Of the 12.5% of patients diagnosed with mood disorders, 5.0% (n = 29) were major depressive disorder, and 6.7% (n = 40) were minor depressive disorder. The odds ratio for co-occurrence of major depressive disorder with generalized anxiety disorders and major depressive disorder with anxiety disorders (NOS) was 11.5 (95% CI: 2.17–18.45) and 8.00 (95% CI: 3.19–20.07), respectively. The PHQ (Patient Health Questionnaire) study in Japan was conducted in eleven primary care sites. A total of 1409 adult patients (611 males, 797 females; mean age: 56.2 years, SD: ±20.4) completed the PHQ in full. The prevalence of diagnosis of any mood disorder or any anxiety disorder was 25.0%. Of the 15.8% of patients diagnosed with mood disorders, 5.3% were for major depression and 8.4% for other depressive disorders. The odds ratio for co-occurrence of major depressive disorder with other anxiety disorders was 30.4 (95% CI: 13.19–70.28).

**Keywords:** anxiety, depression, comorbidity, PRIME-MD, PHQ

## **1. Introduction**

Numerous epidemiological studies in Western countries have shown that anxiety and depressive disorders frequently occur together in [1–4]. Especially, comorbidity of anxiety and depressive disorders has been confirmed in patients presenting in primary care settings [3, 4].

The outcome of co-occurrence of anxiety and depressive disorders is more negative than each single occurrence. According to findings of a large cohort study in the Netherlands, clinically, comorbidity is associated with a greater severity of symptoms, an increased risk of suicide, a more reduced quality of life, and a lower level of functioning [2].

Despite the availability of studies and data examining anxiety and depressive disorders in patients in primary care settings in other countries, such studies are few in Japan. Consequently, recognition of the comorbidity of anxiety and depressive disorders in such patients in Japan remains a major clinical problem. With that issue in mind, here we examine two studies on the comorbidity of anxiety and depressive disorders in Japanese patients in primary care detected by PRIME-MD (Primary Care Evaluation of Mental Disorders) [5, 6] and the PHQ (Patient Health Questionnaire) [7].
